<!DOCTYPE HTML>
<html style="overflow:hidden">
<head>
  <meta charset="utf-8">
  <!-- The viewport tag will result in APZ being in a "zoomed-in" state, assuming
       the device width is less than 980px. -->
  <meta name="viewport" content="width=980; initial-scale=1.0">
  <title>Test for bug 1280013</title>
  <script type="application/javascript" src="apz_test_native_event_utils.js"></script>
  <script type="application/javascript" src="apz_test_utils.js"></script>
  <script type="application/javascript" src="/tests/SimpleTest/paint_listener.js"></script>
  <script type="application/javascript">
function* test(testDriver) {
  SimpleTest.ok(screen.height > 500, "Screen height must be at least 500 pixels for this test to work");

  // This listener will trigger the test to continue once APZ is done with
  // processing the scroll.
  SpecialPowers.Services.obs.addObserver(testDriver, "APZ:TransformEnd", false);

  // Scroll down to the iframe. Do it in two drags instead of one in case the
  // device screen is short
  yield synthesizeNativeTouchDrag(document.body, 10, 400, 0, -(350 + TOUCH_SLOP));
  yield synthesizeNativeTouchDrag(document.body, 10, 400, 0, -(350 + TOUCH_SLOP));
  // Now the top of the visible area should be at y=700 of the top-level page,
  // so if the screen is >= 500px tall, the entire iframe should be visible, at
  // least vertically.

  // However, because of the overflow:hidden on the root elements, all this
  // scrolling is happening in APZ and is not reflected in the main-thread
  // scroll position (it is stored in the callback transform instead). We check
  // this by checking the scroll offset.
  yield flushApzRepaints(testDriver);
  SimpleTest.is(window.scrollY, 0, "Main-thread scroll position is still at 0");

  // Scroll the iframe by 300px. Note that since the main-thread scroll position
  // is still 0, the subframe's getBoundingClientRect is going to be off by
  // 700 pixels, so we compensate for that here.
  var subframe = document.getElementById('subframe');
  yield synthesizeNativeTouchDrag(subframe, 10, 200 - 700, 0, -(300 + TOUCH_SLOP));

  // Remove the observer, we don't need it any more.
  SpecialPowers.Services.obs.removeObserver(testDriver, "APZ:TransformEnd", false);

  // Flush any pending paints
  yield flushApzRepaints(testDriver);

  // get the displayport for the subframe
  var utils = SpecialPowers.getDOMWindowUtils(window);
  var contentPaints = utils.getContentAPZTestData().paints;
  var lastPaint = convertScrollFrameData(contentPaints[contentPaints.length - 1].scrollFrames);
  var foundIt = 0;
  for (var scrollId in lastPaint) {
    if (('contentDescription' in lastPaint[scrollId]) &&
        (lastPaint[scrollId]['contentDescription'].includes('tall_html'))) {
      var dp = getPropertyAsRect(lastPaint, scrollId, 'criticalDisplayport');
      SimpleTest.ok(dp.y <= 0, 'The critical displayport top should be less than or equal to zero to cover the visible part of the subframe; it is ' + dp.y);
      SimpleTest.ok(dp.y + dp.h >= subframe.clientHeight, 'The critical displayport bottom should be greater than the clientHeight; it is ' + (dp.y + dp.h));
      foundIt++;
    }
  }
  SimpleTest.is(foundIt, 1, "Found exactly one critical displayport for the subframe we were interested in.");
}

waitUntilApzStable()
.then(runContinuation(test))
.then(subtestDone);

  </script>
</head>
<body style="overflow:hidden">
  The iframe below is at (0, 800). Scroll it into view, and then scroll the contents. The content should be fully rendered in high-resolution.
  <iframe id="subframe" style="position:absolute; left: 0px; top: 800px; width: 600px; height: 350px" src="helper_tall.html"></iframe>
</body>
</html>
